1. Field of the Invention
The present invention relates to electronic device such as multilayer ceramic capacitor and the like, and method for electronic device.
2. Description of the Related Art
As for one example of electronic device implemented to an electronic apparatus, a multilayer type ceramic electronic device is exemplified, a capacitor, a bandpass filter, an inductor, a piezo element, a PTC thermistor, a NTC thermistor or a varistor and the like have been known.
A capacitor element body of these multilayer type ceramic electronic device is produced, for example, by preparing an angular parallelepiped shape green chip composed by laminating a green chip which becomes a dielectric layer after firing and an internal electrode pattern layer which becomes an internal electrode layer after firing, and co-firing thereof.
Here, as for laminating method for the green sheet and the internal electrode layer patter, for example, there is a method that a green sheet is applied to a base material such as PET film and the like, a sheet unit is formed thereof so that said sheet is sequentially laminated.
However, in this case, although the dielectric layer and the internal electrode layer to form one sheet unit have comparatively sufficient binding strength, binding strength of the internal electrode layer and a dielectric layer of another sheet unit formed on said sheet unit tended to be insufficient. In case that the binding strength of the dielectric layer and the internal electrode layer is insufficient like this, mechanical strength tends to deteriorate.
Thus from the actual circumstances, it has been required an art to improve the binding strength of the internal electrode layer and the green sheet of the other sheet formed on said sheet unit. For example, in a gazette of Japanese Patent laid Open No. 2003-264120, a method that an internal electrode layer is formed on a first ceramic layer which includes a ceramic having an average particle diameter α1, a second ceramic layer which includes a ceramic having an average particle size α2 which is smaller than said average particle size α1, is formed thereon, and combination thereof are laminated sequentially is disclosed.
By this method, although it is considered that the binding strength of the internal electrode layer and the ceramic layer can be obtained, the binding strength of the first ceramic layer and the second ceramic layer is insufficient, because it is only heat pressure bindinging by pressing.
Therefore, as an element body, it becomes insufficient mechanical strength. Also, highly accelerated life time is reduced, because a thickness of the first ceramic layer which includes smaller particle diameter is thinner than a thickness of the second ceramic layer.